Multiple-stage collision avoidance braking system and method

ABSTRACT

An apparatus and method for automatic actuation and control of an air braking system on a commercial vehicle, under a warning of collision conditions, has multiple stages of operation, which supplements the normal brake pedal activation and control of the air brake operation under the driver&#39;s foot control. Automatic actuation has two stages: (1) impending collision automatic activation and control for 1.4 second closure; and (2) imminent collision automatic activation and control for 0.9 seconds closure. A determination of closure occurring in excess of 1.6 seconds, turns off the warning, and also deactivates the automatic activation and control. A modification to a standard air brake system structure enables the addition of the automatic activation and control stages. When an impending collision signal is received, an activation component operates valves to pressurize the rear brakes to 40 psi. When the air pressure at the rear brakes rises to 20 psi, other valves pressurize the front brakes. This first stage automatic operation stops or slows the vehicle with 40 psi on the rear brakes and 20 psi on the front brakes. When an imminent collision signal is received, the activation component opens valves to pressurize the rear brakes to 120 psi. Once the air pressure at the rear brakes rises to 20 psi, the front brakes are also pressurized. This second stage automatic operation stops the vehicle with 120 psi on the rear brakes and 80 psi on the front brakes, unless restricted to a lower pressure by the brake system manufacturer. The driver can deactivate the automatic braking functions by stepping on the brake pedal or by operating the vehicle turn signals.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of co-pending U.S. application Ser. No. 16/188,175, filed Nov. 12, 2018, which is a Continuation of U.S. application Ser. No. 15/439,261, filed Feb. 22, 2017, now U.S. Pat. No. 10,124,777, which issued on Nov. 13, 2018, the disclosures of which are incorporated by reference herein in their entireties.

BACKGROUND OF THE INVENTION

Various types of apparatus have been introduced into the marketplace to provide collision avoidance operation of motor vehicles, principally for collision avoidance of automobiles and light trucks. Most of these systems have been specifically designed for automobiles and light trucks which use hydraulic brake systems. In a hydraulic brake system, brake fluid is used to transmit a hydraulic pressure from the driver's pedal to the foundation brakes, with or without vacuum assistance to increase the pressure. Braking force is dependent to a large measure upon the pressure developed by pressing the brake pedal.

Included in such collision avoidance apparatus are object detection and ranging systems using radar, laser, or optical camera ranging technology to trigger an alarm to the driver, or to adjust the setting of automatic cruise control, or to activate an automated braking system structure.

These systems serve to reduce or eliminate the effect of human reaction time in the presence of a collision threat. They are generally intended for OEM, factory installation.

Present day collision alarm and avoidance systems usually take the form of a warning system or a supplemental brake control system which is microprocessor driven. Some of these systems prematurely control brake light illumination of a proceeding vehicle, as a distance closure warning to a following vehicle, before the brake pedal of the preceding vehicle is operated. Other systems calculate collision mitigation based upon radar, yaw rate, wheel speed, and rear view camera inputs to control power brake booster performance to adjust braking force in a hydraulic system. Many of these systems have electronic controllers which calculate velocity profiles, collision probabilities and provide supplemental brake system instructions.

Braking systems for heavy commercial highway vehicles, such as tractor trailers, heavy straight trucks, and buses, depart from the hydraulic automobile and light truck braking systems, as they are almost exclusively air brake systems. Air brakes can develop a greater stopping force, use simpler components, remain operable even in the presence of a leak, and are generally more safe than hydraulic brakes. Air brakes are found on commercial vehicles with a maximum gross vehicle weight rating (GVWR) of 33,000 pounds or more. They are also often found on vehicles with lesser GVWR, such as 20,000 pounds.

Commercial vehicle air brake systems operate with air pressure from air reservoirs containing a volume of high pressure air, ranging from 60 psi to 120 psi (maximum allowed by D.O.T.), depending upon the design of the braking system. Typically, air reservoirs used in air brake systems are under a pressure of 60-120 psi. There generally is a front circuit to operate the front brakes and a rear circuit to operate the rear brakes. Each circuit has its own air reservoir.

Fail safe air brake systems provide a lesser pressure to service (work) brakes from a second air reservoir in the presence of a failure in the primary service brake circuit. Other systems utilize a lower pressure circuit to control the relay valves of a higher pressure service brake circuit.

Factory available adaptive cruise control systems can electronically set a braking pressure in an air brake system above the default braking pressure, as software resident in the system senses and calculates vehicle factors including speed, yaw rate, lateral acceleration steering angle and traction in regards to predetermined limits for any of these vehicle factors. If the limits are not exceeded, a pressure above the default braking pressure is applied. This process is successively conducted and the pressure is successively increased, based on the successive monitoring and calculating of values in comparison to the predetermined factor limits, until a vehicle deceleration rate of about 2 meters per second is achieved, if possible. Further pressure increases are terminated before the target deceleration rate is achieved if any limit is exceeded.

Very high pressure systems have been proposed for disk brake air systems. However, this technology cannot be operatively applied to present air brake circuits, and it is not yet approved by D.O.T.

In the past, dual pressure air brake systems have been proposed where a higher pressure (120 psi) is generated by an on-board air compressor and stored in a first tank to operate a spring air brake circuit. Air pressure at 120 psi is passed through a pressure reducing valve to be stored at a lower pressure (60 psi) to operate a service air brake circuit. This technology has no application to collision avoidance circuits.

As discussed above, existing collision avoidance systems that have been designed for hydraulic brake systems, are not applicable (transportable) to air brake systems as air brake system components and hydraulic brake system components differ remarkably. The hydraulic system technology is not transportable into air brake system technology. Moreover, existing collision avoidance systems have not been designed for aftermarket installation in older vehicles. Additionally, they have not been designed to operate with various third party warning or detection devices.

The National Highway Traffic Safety Administration (NHTSA) and the Insurance Institute for Highway Safety announced in March 2016, that by 2022, 99% of the new automobiles must have automatic emergency braking systems as a standard feature. Automatic emergency braking systems will similarly, also, soon be required for tractor trailers, and heavy straight trucks and buses.

The features of aftermarket installation and compatibility with existing third party warning and detection devices are important.

It is also important to be able to modify the existing air brake systems on tractor trailers, heavy straight trucks and buses, as these vehicles have long service lives, often extending beyond twenty years or more. These vehicle air brake systems should be able to be modified to meet the new NHTSA standards without replacing the entire air system.

It is desirable that the modifications to existing non-electronic air brake systems also be non-electronic, thereby eliminating or minimizing the need for sensitive electronic components.

It is further desirable that the modified system be able to operate with drive brake pedal air operation as originally installed.

It is also desirable that the system be able to operate with an automatic braking method responsive to an “impending” collision (critical) situation signal, and with an automatic braking method responsive to an “imminent” collision (more critical) situation signal (stage 3).

It is highly desirable that the modifications of the original air brake system, resident in the present invention, leaves the system pneumatically activated and controlled.

SUMMARY OF THE INVENTION

An automatic braking control system and method are provided for controlling the automatic operation of an air brake system on a commercial highway vehicle. The system permits the normal manual operation of the air brakes by the driver's brake pedal, under normal conditions. When a possible collision is detected, the system automatically operates the vehicle's air braking system to avoid or mitigate the collision. The automatic braking system is pneumatically operated and controlled.

The vehicle's factory installed air braking system, in a normal configuration, is employed to stop the vehicle, such as tractor trailer, a heavy straight truck, or a bus, under the foot-operated brake pedal control of the driver. A commercially available collision warning device is used to detect and calculate an impending collision and/or an imminent collision, whereby the “impending” collision is determined to occur within 1.4 seconds and the “imminent” collision is determined to occur within 0.9 seconds.

Where the impending collision automatic braking operation does not stop the vehicle, a second stage operation, i.e., automatic braking for an imminent collision is activated. It is anticipated that the second stage operation will either stop the vehicle or mitigate collision damage. Once the warning device determines a 1.6 second spacing, the collision situation is ended, the automatic activation control ceases, the excess air pressure is bled from the system, and control of the braking is returned entirely to the driver.

The commercial collision warning device constantly calculates “closure time”, based upon the speed of the vehicle with collision avoidance, the foregoing (preceding) vehicle's speed, and the distance between them.

The collision warning device is available from such manufacturers as WABCO Holdings, Inc., and Delphi Automotive, Inc. It is a radar-operated, ranging and closure calculating device which is adjusted to generate both the impending collision signal and an imminent collision signal as conditions dictate.

The driver is always in control of the braking system and can deactivate the automatic braking function by stepping on the brake pedal or by operating the vehicle turn signals. The commercial collision warning system monitors for and reacts to a change of the driver's brake pedal position. It also monitors for and reacts to the operation of the vehicle turn signals.

The invention provides a modification to a standard air brake system structure, which enables additional automatic activation and control stages. This permits an after-market up-grade of the factory air brake system. For the air brake system on a tractor trailer, an actuation apparatus is connected to a commercial collision warning device having signal nodes mounted on the front of the vehicle. This activation apparatus can be a commercially available, solenoid operated, double acting, two position, four way, valve pair. This element can be an Ingersoll Rand model A 312 SD solenoid operated valve which gets its power from a connection to the collision warning device.

The solenoid in the activation apparatus element receives its power from the commercial collision warning device. When the commercial collision warning device detects a change in driver brake pedal position or the activation of the vehicle turn signals, it shuts-off power to the activation apparatus and deactivates the automatic braking operation.

The connection between the collision warning device and the actuation apparatus is hard wired. This is the only non-pneumatic connection in the invention's activation apparatus. The activation apparatus has pneumatic control lines output therefrom. Air pressure is supplied to the actuation apparatus from an air reservoir at its existing pressure, i.e., at 120 psi.

A first pneumatic output from this actuation apparatus is connected to operate a delayed application air control connection element positioned in the air pressure line between the front brake control valve and the air control connection for the front brake actuators. A second pneumatic output from the actuation apparatus is connected to operate an immediate application control connection element positioned in the air pressure line between the rear brake control valve and a rear brake relay valve which leads to the rear brake actuators of a tractor and a trailer brake actuators, if a trailer is present.

Thus, the system uses high pressure air, at 120 psi, to control the state of certain valves which provide the service air pressure to operate the rear and front service brakes. In controlling the air pressure to the vehicle's service brakes, the loss of control of the vehicle's travel path during panic stopping is minimized. Air pressure is always first applied to the rear service brakes, before it is applied to the front service brakes. Air pressure is applied to the front brakes only after (when) a threshold pressure value has been achieved on the rear brakes. Moreover the service air pressure to the rear and front brakes is always controlled so that the rear pressure is always higher than the front pressure. The rear pressure is significantly higher than the front pressure. This assures that the rear brakes are always physically engage before the front brakes and the rear brake stopping force is greater than at the front brakes. This eliminates or minimizes the possibility of a jackknife, or side skidding of the rear of the vehicle.

The activation apparatus, a dual operation solenoid valve pair receives air pressure from an air pressure reservoir to be selectively passed into the invention piping in response to signals from the collision warning device. The activation apparatus is normally closed, and provides air pressure at a first output when an impending collision signal is present, and air pressure at second output when an imminent collision signal is present. Only one output of the activation apparatus can be active at a time.

When an impending collision signal is received indicating a collision in approximately 1.4 seconds, the activation apparatus component controls valves opening to pressurize the rear foundation brakes to 40 psi, with air from a rear air reservoir. When the air pressure at the rear brakes rises to 20 psi, other valves are controlled to pressurize the front brakes with air from a front air reservoir. This automatic operation stops or slows the vehicle with 40 psi on the rear brakes and 20 psi on the front brakes.

When an imminent collision signal is received indicating a collision in approximately 0.9 seconds, the activation component enables valves to open to pressurize the rear brakes to 120 psi with air from the rear air reservoir. When the air pressure at the rear brakes rises to 20 psi, the front brakes are pressurized with air from the front air reservoir. This automatic operation stops the vehicle with 120 psi on the rear brakes and 80 psi on the front brakes, unless restricted to a lower pressure by the brake system manufacturer. For example some air brake equipment can only tolerate lower pressures, such as 80 psi on the rear circuit and 60 psi on the front circuit.

By having this braking sequence of the rear service brakes and the front service brakes, the rear tires always want to stop faster than the front tires. This eliminates or minimizes the tendency to fishtail, jackknife or the vehicle rolling over.

The present invention provides a modification to a standard air brake system structure, which enables the additional automatic activation and control stages. In the presence of an impending collision signal (1.4 seconds closure) the activation component opens valves to pressurize the rear service brakes are pressurized to about 40 psi, with air from a rear air reservoir. When the air pressure at the rear brakes rises to about 20 psi, other valves are opened to pressurize the front brakes with air from a front air reservoir. This automatic operation stops or slows the vehicle with about 40 psi on the rear brakes and about 20 psi on the front brakes. In the presence of an imminent collision signal (0.9 seconds closure), the activation component enables valves to open to pressurize the rear brakes to about 120 psi with air from the rear air reservoir. When the air pressure at the rear brakes rises to about 20 psi, the front brakes are pressurized with air from the front air reservoir to about 20 psi. Thus, this automatic operation stops the vehicle with about 120 psi on the rear brakes and about 80 psi on the front brakes.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be understood from a reading of the following description and the attached claims, in connection with the accompanying drawings, in which like numerals refer to like elements and in which:

FIG. 1 is a block diagram for the invention system;

FIG. 2 shows the braking distance curve for an air brake system operating normally, with manual brake actuation from brake pedal operation;

FIG. 3 shows the braking distance curve with automatic brake actuation of the present invention; and

FIG. 4 shows the braking distance curve of the invention when coupled with an optional electromagnetic retarder on the drive shaft or on a rear axle.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a pneumatically operated and pneumatically controlled automatic braking control system and method for controlling air brakes on a commercial highway vehicle. The system operates in multiple stages. There is normal manual operation of the air brakes by the driver's brake pedal under normal conditions. When a possible collision is detected, the system automatically operates the vehicle's air braking system, by first applying air pressure to the rear brakes. When the pressure at the rear brakes has reached 20 psi, air pressure is applied to the front brakes. The air pressure applied on the rear brakes is ultimately 40 psi, and on the front brakes is ultimately 20 psi.

In a next stage, air pressure is also first applied to the rear brakes. When the rear brake pressure reaches 20 psi, air pressure is fed to the front brakes. In this stage, the air pressure on the rear brakes is ultimately 120 psi and on the front brakes is 80 psi. These pressures are reduced when required by the manufacturer's specifications.

The initial stage is activated when the vehicle is calculated to be approximately 1.4 seconds from impact. The next stage is activated when the vehicle is calculated to be approximately 0.9 seconds from impact.

FIG. 1 shows a block diagram of the structure of the invention. In a driver operated mode, a driver operated brake pedal 21 operates a rear brakes control valve 23 and a front brakes control valve 25, concurrently. The rear brake control valve 23 receives air pressure from a rear air reservoir 45 via a pneumatic line 44. The front brake control valve 25 receives air pressure from a front air reservoir 29 via a pneumatic line 31.

The output from the rear brake control valve 23 is connected to a rear service brake relay valve 51 via pneumatic line 52. Rear relay valve 51 then passes air pressure onto a left and a right rear ABS module 55, 57 via pneumatic line 53. The left and right rear ABS modules 55, 57 respectively feed left and right tandem brake actuators 59, 61.

The rear relay valve 51 via an additional pneumatic line 70 passes air pressure through a tractor protection valve 75 to a trailer service brake line 77, if a trailer is present.

The output from the front brake control valve 25 is connected to a front “T” connector gate 36 though a pneumatic line 81. Front connector gate 36 passes air pressure to a left and a right ABS module 37, 39 via a pneumatic line 40. Left and right ABS modules 37, 39 feed air pressure to left and right front brake actuators 41, 43, respectively.

A commercial warning device 11 is employed to detect collision conditions and to send signals indicating one or the other of two collision conditions, “impending” or “imminent”. The output from the warning device 11 is three electrical wires 15, a “high” signal, a “low” signal and a ground. The low signal indicates an impending collision. The high signal indicates an imminent collision. No signal indicates a non-collision situation. Electrical connection cabling 15 powers (i.e., drives) an actuation apparatus 13, which actuator is an electronic, two stage, solenoid operated, air valve. The actuation apparatus 11 has two outputs. The first output is connected to a pneumatic line 19, while the second output is connected to a pneumatic line 79.

An “impending” collision (i.e., closure) indicates a collision in 1.4 seconds. An “imminent” collision indicates a collision (i.e., closure) indicates a collision in 0.90 seconds. A closure equal to or greater than 1.6 seconds is a non-collision condition.

The air pressure in the front air reservoir 29 is about 120 psi. The air pressure in the rear air reservoir is also kept at about 120 psi. Pneumatic line 49 feeds the 120 psi pressure to the actuation apparatus 11, which in turn feeds a one-way connector gate 71, via the pneumatic line 19. A pneumatic line 85 exits the one-way gate 71 and connects to a pressure regulator, step down gate 69. Regulator gate 69 can be adjustable. Regardless, it reduces the 120 psi from the actuation apparatus 11 to a pressure of 40 psi. The output of regulator gate 69 is connected to a connection “T” gate 83. An output line 84 from gate 83 is connected into a crack valve 36. The output of the crack valve 35 is connected into the front “T” connector gate 36 to ultimately lead to the front brake actuators 37, 39. The crack valve 35 operation may be adjustable. The crack valve 35 of the present invention is set to quickly release (open) at 20 psi.

Another pneumatic line from the “T” connection gate 83 is connected into a “T” connection gate 73. A pneumatic line from gate 73 connects to a connector “T” gate 65 via a pneumatic line 72. The gate 73 is also connected to an output from the rear brake control valve 23. The second output from the actuation device 11 via a pneumatic line 79 connects with the connector gate 79 which is connected to the input 67 of the rear relay valve 51 via a pneumatic line 63.

Air pressure is output from the actuation apparatus 11 via line 19 in an “impending” collision condition, i.e., where there is about 1.4 seconds of closure time until impact. In this situation there is no air pressure on line 79 from the other output actuator 11.

Air pressure is output from the actuation apparatus 11 via line 79 in an “imminent” collision condition, i.e., where there is about 0.9 seconds of closure time until impact. In this situation there is no air pressure on line 19 from the other output from actuator 11.

As an option, an electro-magnetic retarder device may be added, to be mounted to a rear axle or to the drive shaft to contribute additional braking action. Such retarders are frictionless stopping aids which are used to slow vehicles to prevent the service brakes from overheating and to minimize stopping distance. Retarders are commercially available from such manufacturers as Frenelsa S.A., Telma, S.A., Cama Products, Kimbo/Sharp Corporation and others.

When 1.4 seconds to impact is detected, the invention sends air pressure from rear reservoir 45 through the actuator 11, FIG. 1. Then via line 19 though gate 71, via line 85, through gate 69, through regulator 69, though gate 83, and via line 84 to wait for crack valve 35.

Air pressure also flows though gate 83, through gate 73, via line 72 to gate 65, and there through. The air pressure travels via line 63 to input 67 and through relay gate 51 to the rear brakes. The other output from actuator 11 is closed.

When the pressure at the rear brakes relay valve 51 rises to 20 psi, there is also 20 psi at the crack valve 35. Crack valve 35 then opens and air pressure begins to build on the front brakes as it continues to increase on the rear brakes. The rear brake pressure is higher than the front brake pressure and remains so. The pressure is held with 40 psi on the rear brakes and 20 psi on the front brakes to stop the vehicle. When a trailer is present, trailer brake pressure will approximate the rear brake pressure at 40 psi.

When 0.9 seconds to impact is detected, the invention send air pressure from rear reservoir 45 through the actuator 11, and then via line 79 to the gate 65. The other output port from actuator 11 is closed.

The pressure at gate 65 is sent via line 63 to the rear relay valve 51 and via line 72 to gate 73. From gate 73 the pressure passes through the gate 83 and then via line 84 to the crack valve. When the pressure at the crack valve rises to 20 psi the crack valve opens and pressure begins to build on the front brakes, while continuing to rise on the rear brakes. The rear brake pressure is higher that the front brake pressure and remains so. A pressure of 120 psi is held on the rear brakes and 80-100 psi on the front brakes to stop or slow the vehicle. Again, when a trailer is present, the trail brake pressure will follow the rear brake pressure at 120 psi.

The operation of the invention, including following distance, response time and vehicle speed, is shown in FIG. 3, and can be compared with the same factors for the operation of a manual braking system, FIG. 2, and the same factors for the operation of the invention coupled with a commercial electro-magnetic retarder mounted to the vehicle drive shaft, or rear axle. These graphs were generated from test results obtained by operating the same test vehicle, which was first-operated with manual braking, then, secondly, with the collision avoidance braking invention in place, and lastly, with a drive shaft mounted retarder or rear axle mounted retarder added to the invention.

In each of these graphs (FIGS. 2, 3, 4) the solid line 87 shows vehicle following distance. Each of the graphs show a closure, i.e., a reduction in following distance of the test vehicle with respect to a preceding vehicle. For the manual system, FIG. 2, the response time, once a collision warning is generated, is shown as time of driver collision recognition 91, driver response 93, and brake response 95. For the present invention, FIG. 3, the response time once a warning is generated, is indicated by brake response 95 followed by brake deceleration 97. It is important to note that brake deceleration 97 is shown to occur much sooner in FIGS. 4 and 5, than in FIG. 3.

The next important factor to note is the time of closest vehicle approach 99. This is the demarcation point, where the test vehicle braking action results in an increase in the distance to the foregoing vehicle, thereby avoiding a collision. This factor relates to the speed curve 101 of the braking vehicle which shows a reduction in speed 101, FIGS. 2, 3, 4, during braking. This speed reduction is seen to occur soonest in FIG. 4. The time to speed reduction is seen to be slightly less in FIG. 3. FIG. 2 shows the largest delay before a speed reduction occurs.

Once braking has occurred, the driver must make an evaluation 103. The driver controls the acceleration 105 of the vehicle 105 if conditions warrant. Once a safe distance is achieved 107, driver acceleration is ended 109.

With manual braking, FIG. 2, the warning duration 111 extends from the start of the warning signal 89 to the time a safe distance is achieved 107. With the invention, FIG. 3, the warning duration 111, is less, as it extends from the start of the warning signal 89 to the achievement of a safe distance 107 at the beginning of driver evaluation 103.

With the addition of an electro-magnetic retarder, FIG. 4, warning duration 111 is further shortened and additional braking improvement 113 occurs. This improvement 113 is shown as the time from the achieved safe distance 107 time, to the time almost to the termination of driver controlled acceleration 109.

The following elements are shown in the accompanying drawings.

-   11 collision warning device -   13 actuation apparatus—electronic, two stage, solenoid operated, air     valve -   15 electrical connection cabling—HLG (high low ground) cable wire -   19 pneumatic line from actuation apparatus 11 to gate 71 -   21 driver brake pedal -   23 rear brakes control valve -   25 front brakes control valve -   29 front air reservoir -   31 pneumatic line from front air reservoir 29 to front brakes     control valve 25 -   35 quick release crack valve -   36 front “T” connector gate -   37 left front ABS -   39 right front ABS -   40 pneumatic line from connector gate 36 to ABS 37 and 39 -   41 left front actuator -   43 right front actuator -   44 pneumatic line from rear air reservoir to rear control valve 23 -   45 rear air reservoir -   47 air supply connector -   50 pneumatic line from rear brake control valve 25 to relay valve 51 -   51 service brake relay valve -   53 pneumatic output to rear ABS 55 and 57 -   55 left rear ABS -   57 right rear ABS -   59 left rear brake actuator -   61 right rear brake actuator -   63 pneumatic feed from gate 65 to rear relay valve input 67 -   65 connector “T” gate -   67 input for rear relay valve 51 -   69 pressure regulator step down gate 120 psi to 40 psi -   70 pneumatic line from rear relay valve to tractor protection valve     75 -   71 one-way connector gate -   72 pneumatic line from gate 73 to gate 65 -   73 pneumatic “T” connection gate between gate 83 and rear control     valve 23 -   75 tractor protection valve -   77 trailer service brake line -   79 pneumatic line from activation apparatus 11 to connector gate 65 -   81 pneumatic line from front brake control valve 25 to front “T”     connector gate 36, which -   connector gate also is connected to the output from crack valve 35 -   83 pneumatic connection “T” gate from pressure reducer 69 -   84 pneumatic line from gate 83 to crack valve 35 -   85 pneumatic line from one-way gate 71 to pressure reducer 69 -   87 solid line following distance -   89 collision warning -   91 driver recognition -   93 driver response -   95 brake response -   97 brake deceleration -   99 time of closest approach -   101 speed curve -   103 driver evaluation -   105 driver acceleration -   107 safe distance achieved -   109 acceleration ended -   111 warning duration -   113 improvement in braking

The foregoing description is intended to be illustrative of the invention. Modifications and substitutions may be introduced without departing from the scope or intent of the described invention or the accompanying claims. 

What is claimed:
 1. A method of automatic braking, collision avoidance for vehicle air brake systems, including the steps of: detecting an impending collision condition; pressurizing the rear brakes with a source pressure of about 40 psi when said impending collision condition is detected; pressurizing the front brakes when the pressure at the rear brakes has risen to about 20 psi; and maintaining an air pressure of 40 psi at the rear brakes and 20 psi at the front brakes to slow or stop the vehicle.
 2. The method of collision avoidance of claim 1, including the steps of: detecting an imminent collision condition; pressurizing the rear brakes with a source pressure of about 120 psi when said imminent collision condition is detected; begin pressurizing the front brakes when the pressure at the rear brakes has risen to about 20 psi; and maintaining an air pressure of about 120 psi at the rear brakes and about 80 psi at the front brakes to slow or stop the vehicle.
 3. The method of collision avoidance of claim 1, including the steps of: detecting an imminent collision condition; pressurizing the rear brakes to a pressure of about 80 psi when said imminent collision condition is detected; begin pressurizing the front brakes when the pressure at the rear brakes has risen to about 20 psi; and maintaining an air pressure of about 80 psi at the rear brakes and about 60 psi at the front brakes to slow or stop the vehicle.
 4. The method of collision avoidance of claim 1, including releasing said brake pressure and returning brake operation entirely to the driver when a non-collision condition is detected.
 5. The method of collision avoidance of claim 1, wherein said impending collision is determined to occur in about 1.4 seconds.
 6. The method of collision avoidance of claim 2, wherein said imminent collision is determined to occur in about 0.9 seconds.
 7. The method of collision avoidance of claim 4, wherein said non-collision condition is determined by a closure of greater than 1.6 seconds.
 8. The method of collision avoidance of claim 1, including maintaining a front air pressure reservoir at 120 psi, and a rear air pressure reservoir at 120 psi, and pressurizing said rear brakes from said rear reservoir, and pressurizing said front brakes from said front reservoir.
 9. The method of collision avoidance of claim 2, including maintaining a front air pressure reservoir at 120 psi, and a rear air pressure reservoir at 120 psi, wherein said pressurizing of said rear brakes is from said rear reservoir, and said pressurizing of said front brakes is from said front reservoir.
 10. The method of collision avoidance of claim 8, wherein the step of pressurizing the rear brakes includes opening at least one valve between said rear air pressure reservoir and said rear service brakes with an air control pressure of 120 psi, and opening at least one valve between said front air pressure reservoir and said front service brakes with an air control pressure of 120 psi.
 11. The method of collision avoidance of claim 8, wherein the step of pressurizing the rear brakes includes opening at least one valve between said rear air pressure reservoir and said rear service brakes with an air control pressure of 120 psi, and opening at least one valve between said front air pressure reservoir and said front service brakes with an air control pressure of 120 psi.
 12. An automatic braking collision avoidance system, for a commercial vehicle air brake system, having a front brake circuit and a rear brake circuit, comprising: a collision warning device providing a signal representing closure time with a foregoing vehicle or object, including an impending collision warning signal and an imminent collision warning signal; a rear air pressure reservoir, and a front air pressure reservoir, where the pressure in said rear and front reservoirs is each maintained at the same pressure; an actuation apparatus element being electrically connected to said collision warning device for reacting to an impending collision warning signal and to an imminent collision warning signal; at least one connection element in a pneumatic pressure line between said rear air pressure reservoir and said rear service brake circuit, wherein said connection element operates as a valve; at least one connection element in a pneumatic pressure line between said front air pressure reservoir and said front service brake circuit, wherein said connection element operates as a valve; wherein when an impending collision warning signal is detected, said actuation apparatus first controls said rear air service brake pressure to pressurize said rear brake circuit such that when said rear brake pressure reaches a first threshold, said actuation apparatus controls said front air service brake pressure to pressurize said front brakes; wherein when the pressure at said rear brakes and the pressure at said front brakes each reach its predetermined target pressure, further pressure increases are ceased and the target pressures are maintained.
 13. The automatic braking collision avoidance system of claim 12, wherein when an imminent collision warning signal is detected, said actuation apparatus first controls said rear air service brake pressure to pressurize said rear brake circuit at a target pressure of said rear air reservoir pressure, wherein when said rear brake pressure reaches a first threshold, said actuation apparatus controls said front air service brake pressure to pressurize said front brakes to a target pressure of less than said rear brake target pressure, wherein when said rear brake pressure and said front brake pressure each reach the predetermined ultimate target pressures, further air pressure increases are ceased, and the ultimate target pressures are maintained.
 14. The automatic braking collision avoidance system of claim 12, wherein the first threshold pressure at said rear brakes is about 20 psi, and wherein the predetermined target pressure at which said air pressure increases are ceased is at about 40 psi for said rear brakes, and at about 20 psi for said front brakes.
 15. The automatic braking collision avoidance system of claim 13, wherein said rear air pressure reservoir and said front air pressure reservoir are each at about 120 psi, and wherein the rear brake pressure threshold for activating said front brake pressure is about 20 psi, and wherein the predetermined ultimate target pressure at said rear brake circuit is 120 psi and at said front brake circuit is about 80 psi.
 16. The automatic braking collision avoidance system of claim 12 wherein said valve action between said rear air pressure reservoir and said rear service brake circuit is controlled with a high pressure pneumatic signal from said actuation apparatus, which pneumatic control signal passes through a delayed operation gate pneumatically connected to a rear brake control valve, the operation of said delayed operation gate being controlled by a separate pneumatic control signal form said actuation apparatus.
 17. The automatic braking collision avoidance system of claim 12 wherein said actuation apparatus element is an electronic solenoid operated two stage valve.
 18. The automatic braking collision avoidance system of claim 13, wherein said actuation apparatus element is an electronic solenoid operated two stage valve.
 19. The automatic braking collision avoidance system of claim 18, also including a quick release crack valve connected to the front brakes, a front brake control valve pneumatically powering said crack valve.
 20. A method of automatic braking, collision avoidance for vehicle air brake systems, including the steps of: receiving a collision indication signal; pressurizing the rear brakes with a first higher pressure when said collision indication signal is detected; pressurizing the front brakes when the pressure at the rear brakes has risen to a first threshold value which is less than said first higher pressure, said pressurizing maintaining a pressure differential between a higher rear brake pressure and a lower front brake pressure; and maintaining an higher air pressure of at the rear brakes and a lower air pressure at the front brakes at said pressure differential, to slow or stop the vehicle. 